In situ microscale variation in distribution and consumption of O2: A case study from a deep ocean margin sediment (Sagami Bay, Japan)
In situ microscale variation in distribution and consumption of O2: A case study from a deep ocean margin sediment (Sagami Bay, Japan)
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DOI：
10.4319/lo.2009.54.1.0001
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发表时间：
2009-01-01
影响因子：
4.5
通讯作者：
Kitazato, Hiroshi
中科院分区：
文献类型：
--
作者：
Glud, Ronnie N.;Stahl, Henrik;Kitazato, Hiroshi
横断显微剖面仪记录了 1450 米水深（日本相模湾）底栖 O-2 浓度的明显小范围变化。单次部署期间获得的数据显示，在 190 cm(2) 的沉积物区域内，O-2 渗透深度从 2.6 mm 到 17.8 mm（平均；6.6 +/- 2.5 mm）变化，并且根据扩散边界层内的垂直浓度梯度计算得出的扩散 O-2 吸收范围从 0.6 mmol m(-2) d(-1) 到 3.9 mmol m(-2) d(-1)（平均值；1.8 +/- 0.7 mmol m(-2) d(-1)，n = 129）。然而，微形貌和水平扩散的校正使平均扩散 O-2 吸收增加了 1.26 +/- 0.06 倍。对特定体积 O-2 消耗量的详细二维计算显示出很高的可变性。含氧区的特点是活动水平明显不同的沉积物块镶嵌。 O-2 消耗率高达 10 pmol cm(-3) s(-1) 的毫米至厘米大小的“热点”被低或微不足道的 O-2 消耗量分开。有氧活动的变化必然反映了电子供体的不均匀分布，并表明有氧区内物质的周转在很大程度上仅限于热点。在四次航行期间测量的原位海底 O-2 吸收量反映了覆盖观察到的小规模变化的季节性信号。每年的底栖矿化平衡相当于估计的中上层产量的 50%。然而，中央海湾的特点是有显着的下坡沉积物输送，质量平衡估计表明，到达中央海湾底部的总有机物质有 90% 被保留。
A transecting microprofiler documented a pronounced small-scale variation in the benthic O-2 concentration at 1450-m water depth (Sagami Bay, Japan). Data obtained during a single deployment revealed that within a sediment area of 190 cm(2) the O-2 penetration depth varied from 2.6 mm to 17.8 mm (average; 6.6 +/- 2.5 mm) and the diffusive O-2 uptake, calculated from the vertical concentration gradient within the diffusive boundary layer, ranged from 0.6 mmol m(-2) d(-1) to 3.9 mmol m(-2) d(-1) (average; 1.8 +/- 0.7 mmol m(-2) d(-1), n = 129). However, correction for microtopography and horizontal diffusion increased the average diffusive O-2 uptake by a factor of 1.26 +/- 0.06. Detailed 2D calculations on the volume-specific O-2 consumption exhibited high variability. The oxic zone was characterized by a mosaic of sediment parcels with markedly different activity levels. Millimeter- to centimeter-sized "hot spots" with O-2 consumption rates up to 10 pmol cm(-3) s(-1) were separated by parcels of low or insignificant O-2 consumption. The variation in aerobic activity must reflect an inhomogeneous distribution of electron donors and suggests that the turnover of material within the oxic zone to a large extent was confined to hot spots. The in situ benthic O-2 uptakes, measured during four cruises, reflected a seasonal signal overlying the observed small-scale variability. The annual benthic mineralization balanced similar to 50% of the estimated pelagic production. However, the central bay is characterized by a significant downslope sediment transport, and mass balance estimates indicate 90% retention of the total organic material reaching the bottom of the central bay.